Question

Pure Si at 300 K has equal electron (ni) and hole concentration (p) of 1.5 X 10^16 m^-3. Doping by indium increases p to 4.5 X 10^22 m^-3. What is n in the doped silicon?

(a) 4.5 X 10^9 m^-3

(b) 4.5 X 10^22 m^-3

(c) 5 X 10^9 m^-3

(d) 5 X 10^22 m^-3

Answer 1

The correct choice is (c) 5 X 10^9 m^-3

Best explanation: Here, ni = 1.5 X 10^16 m^-3, p = 4.5 X 10^22 m^-3

We know, np = ni^2

n = ni^2/p

= 5 X 10^9 m^-3.